SU757994A1 - Device for measuring parameters of single shock pulses - Google Patents

Description

621.317.7

(088.8)

one

The invention relates to electrical engineering, in particular, to the technique of measuring fast processes together with a non-electric primary transducer, intended for studying shock, explosive processes, studying the behavior of materials, devices under shock loading or other physical or chemical K

phenomena occurring in a short period of time.

There are known devices for measuring peak values of single signals and measuring time intervals from the moment of appearance of a signal to its amplitude value, based on sequentially connected peak detectors with a gradually increasing time constant 2 (discharge storage capacitors untied by cathode repeaters [1].

In such devices, it is possible to ensure that the peak value of the 2Ϊ input signal is stored only for a short time, measured in units of seconds. This is due to the relatively low reverse resistance of the diodes through which zapami-3 is discharged (

2

capacitor capacitor. In addition, lamps with highly efficient cathode emission, which are known to have a short service life, are necessary.

Also known are devices for measuring parameters of single shock pulses, which contain a channel for measuring the maximum pulse value, which includes a comparison device, the first input of which serves as an input to the device and is connected to an initial bias circuit, and the output is connected to a diode, in series with which a charging transistor, a storage capacitor, connected to the input of the voltage follower, the output of which is connected to the second input of the comparison device, through a switch to the input of the measuring device Twa through protective Zener diode - to the common bus and the device through the resistive voltage divider with its inverting input, and measuring the channel pulse width to its maximum value, whose input is connected to the output of the comparator [2].

The disadvantage of this device is

It is as follows.

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The device does not allow you to get a long time of remembering the peak value, since the charging diode has a relatively large reverse leakage current. The desire to increase the time of memorizing the amplitude value of a single signal by increasing the capacitance of the storage capacitor leads to an increase in the dynamic error of the amplitude memory of the pulse.

The aim of the invention is to increase the accuracy of measurement of parameters of shock pulses.

This goal is achieved. In the device for measuring parameters of single shock pulses, containing a channel for measuring the maximum pulse value, including a comparison device, the first input of which serves as the device input and is connected to the initial bias circuit, and the output with a diode, in series with the charging a transistor, a storage capacitor connected to the input of the voltage follower, the output of which is connected to the second input of the comparison device, through a switch to the input of the measuring device through a protective Zener diode — with a common device bus and through a resistive voltage divider — with its inverse input, c the pulse width measurement channel to the maximum value, the input of which is connected to the output of the comparison device, the base of the charging transistor is connected to the output of the voltage follower, and the emitter through the equalizing resistance is connected to the base of this transistor, and how to measure the pulse duration to the maximum value is made in the form of an input pack introduced into the device ulation key, a current source, a storage capacitor and a second channel for measuring the maximum value of the pulse, the output key and a current source connected to the storage capacitor and the input of the second measurement channel maximum pulse, and the output of the last switch is connected through to the measuring device.

The drawing shows a functional diagram of the device.

The device comprises a channel for measuring the maximum value of pulse 1, consisting of a comparison device 2, made, for example, on the basis of an operational amplifier; comparing device 2 has two inputs, 'one of them is the first input (indicated by the sign comes

the input signal, and the second - an inverted input (indicated by a sign - connected to the output of the maximum value measurement channel, besides the comparing device 2, channel 1 contains a diode 3, a charging transistor 4, a storage capacitor 5, a voltage follower made, for example, at an operational amplifier 6 field-effect transistor, resistive divider 7,

8, protective Zener diode 9, leveling resistor 10, bit button 11, measuring device 12, * channel measuring the time interval from the beginning of the input pulse to its maximum 13, consisting of a DC generator 14, a controlled switch 15, a storage capacitor 16, the second measurement channel the maximum value of the pulse 17, the second bit button 18.

The circuit of the initial offset 19 and the switch 20.

The device works as follows.

The input signal is fed to the input "+" of the comparator device 2. To the same point is connected through the source bias source limiting resistance. The output of the comparison device 2 is connected to a charging circuit consisting of a series-connected diode 3, a transistor 4, a storage capacitor 5, and is also connected to the control input of the switch 15, the output of which in its initial state shunts the capacitor 16 connected to the DC source 14 and to the input the device registering the maximum voltage level 17 on the capacitor 16. The output of channel 1 and the output of device 17 is connected to the input of a measuring device of constant voltage 12. In order to protect the operational amplifier, I compare From a high voltage level, the second input of this amplifier is shunted by a zener diode 9. A matching stage at the operational amplifier b is connected in a repeater circuit with a voltage transfer ratio equal to one. This is achieved by an appropriate choice of resistors 7 and 8. In the ideal case, when the voltage gain of the operational amplifier 6 is equal to oo, · the value of resistor 7 is zero. In a reversal amplifier, the value of resistor 7 is 0.5-2% of the value of resistor 8.

Before starting, the device is reset to its original state by pressing the buttons 11.18. Capacitors 5 and 16 are discharged at the outputs. Outputs 21 and 22 form a zero initial voltage.

Due to the action of the bias circuit 19, which creates a small voltage drop on the internal resistance of the signal source and on the input resistance of the comparison device 2, a negative voltage is generated at the output of the comparison device 2

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thanks to which the key 15 is reliably opened and the current of the constant current source 14 passes through this public key 15. At the inverse input of the comparator device 2 and at the base of transistor 4, the voltage is almost zero.

With the arrival of a positive signal (when its instantaneous value exceeds the level of the initial displacement by several millivolts), the output of the comparison device 2 acquires a positive potential, the charging of the capacitor 5 begins. At the same time, the key 15 closes and the charging of the capacitor 16 begins. Moreover, the capacitor 5 is charged by the current of the comparison device 2 open transistor 4, and the capacitor 16 is charged according to the linear law of the current generator 14.

In the process of increasing the input signal, the voltage on the capacitor 5 will monitor the input signal, because if the voltage at the output of the amplifier 6 exceeds the instantaneous voltage at the signal input of the comparison device 2, the latter switches to the negative output voltage, and transistor 4 closes, which causes charge capacitor 5, i.e. the charging process is continuously regulated by the comparison device 2 and the transistor 4, which is essentially a resistor, the value of which depends on the voltage across the capacitor 5.

At that moment, when the input voltage reaches a maximum value, i.e. The first time derivative of the input signal becomes zero, and then changes its sign, the process of charging the capacitor 5 and the capacitor 16 ends, since the voltage at the first input of the amplifier of the comparison device 2 becomes less than the voltage at the other input, resulting in the output voltage comparing device 2 changes its sign to reverse, which leads to the closure of the transistor 4 and the opening of the key 15.

Since channel 17 is made in the same way as channel 1, a voltage proportional to the charging time of capacitor 16 will be fixed at its output.

Improving the accuracy of measurement in this device is achieved due to the lack of discharge of the capacitor 5 through a charging circuit consisting of transistor 4 and diode 3. Diode 3 and resistor 10 in this case protect transistor 4 from breakdown by reverse voltage applied to the base-emitter junction after the process ends charge capacitor. Thanks to the inclusion of a resistor 10 sum-.

ma voltage is applied mainly to the diode 3, the transition emitter-base of the transistor 4 is under reverse voltage, close to zero. Charges do not come from the collector area, since the base area and the collector area are equipotential. This ensures a long storage time of the charge of the capacitor 5, even if its value is small, and it also becomes possible to obtain a high charge rate of the storage capacitor 5, i.e. virtually eliminate the dynamic inaccuracy of memorization, without fear of overshooting due to this method of switching on the charging transistor.

The inverse input of the comparing device 2 is protected by a zener diode 9, which does not affect the operation of channel 1 if the level of its output voltage does not exceed the maximum permissible value determined by the breakdown voltage of the zener diode.

The use of channel 17, similar to 1, and key 15, controlled by a comparing device 2, allows for a sufficiently accurate measurement of the second parameter of the impact impulse duration of the pulse from its beginning to its maximum value. Due to the features of the circuit solution noted above, the device as a whole acquires the following advantages: it provides higher accuracy of measurement of the parameter of shock single pulses (measurement error less than one percent), long information memorization time (memory time can reach several hours), allows reducing the cost of additional measuring instrumentation, which is very important for multi-channel measurements.

Claims (1)

Claim A device for measuring parameters of single shock pulses, containing a channel for measuring the maximum value of a pulse, including a comparing device, the first input of which serves as an input to the device and is connected to an initial bias circuit, and the output to a diode in series with a charging transistor that stores a capacitor connected to the input of the voltage follower, the output of which is connected to the second input of the comparison device, through a switch to the input of the device, through a protective zener diode with a common bus devices and through a resistive voltage divider - to its inverting input, and measuring the channel pulse width to mak7 757994 eight the maximum value, the input of which is connected to the output of the comparison device, characterized in that, in order to improve the measurement accuracy, the base of the charging transistor is connected to the output of the voltage follower, and the emitter through. the equalizing resistance is connected to the base of this transistor, and the pulse width measurement channel to the maximum value is made in the form of an input controlled key entered into the device, a current source, a storage capacitor and a second pulse maximum measurement channel, the key outputs and the current source are connected to a storage capacitor and input the second channel of measurement of the maximum value of the pulse, and the output of the latter through a switch is connected to the measuring device.